DEMINERALIZATION OF SWEET LACTOSUERO OF QUESERÍADESCRIPTION The invention relates to the field of demineralization of sweet whey cheese. The demineralized whey, liquid or powder, is the main component of children's and dietetic products, in particular milks adapted to breast milk. The demineralized whey also has other applications, for example as a substitute ingredient for skim milk in confectionery-chocolate making or in the manufacture of reconstituted milks. The known methods of demineralization of the most effective dairy products and derivatives are electrodialysis and ion exchange, which are applied separately or in combination. In electrodialysis, the ionized salts in solution in the whey migrate under the effect of an electric field through the membranes selectively permeable to cations and anions and are eliminated in the form of brine. In the exchange of ions, the ionic equilibrium between a resin as a solid phase and the whey that is going to be demineralized as a liquid phase is used; the ions are adsorbed on the resin of the same nature at the time of the saturation phase, and then the regenerated resins. For reasons of productivity, these two techniques are advantageously combined in a two-stage procedure; the electrodialysis ensures a first demineralization at approximately 50 ° C / 60 ° C and the exchange of ions, preferably multi-levels, with successive weak cationic and strong cationic resins, performing the termination demineralization at 90 ° C / 95 ° C, as described for example in US-A-4803089. These procedures have the disadvantage that the ion exchange stage requires large amounts of chemical regenerants and consumes a lot of water and that electrodialysis can not be used beyond a demineralization rate > to 60%, due to its high demand in electric power. The electrodeionization that forms the object, for example, of US-A-4632745 or of US-A-5120416, performs continuous deionization in water treatment by combining electrodialysis and ion exchange in a single module, which presents the advantages of small consumption of water and energy and eliminates the need to chemically regenerate the resins. This technique consists of circulating the water to be demineralized, through a set of cells in parallel bounded by semi-permeable cationic and ionic membranes and containing a mixture of resin balls, called dilution compartments; these dilution compartments are separated from each other and their set is separated from the outside with spacers, forming so-called concentration compartments, delimited by semi-permeable anionic and cationic membranes; the assembly is placed between a cathode compartment and an anode compartment under tension. Washed water is circulated in the concentration spaces, which allows to eliminate in the form of effluent, the ions that are concentrated in them, due to the fact of their polarity, migrating through the membranes under the effect of the electric field from the dilution compartments to the concentration compartments. Differently from electrodialysis, resin beads loaded with adsorbed ions maintain a satisfactory electrical conductivity in the dilution compartments throughout this demineralization process. In addition, it is not necessary to regenerate them, since the sites saturated in cations or in anions are exchanged as measured against H + and OH "ions under the effect of the electric field In the process according to US-A-4632745, the resin balls are they are fixedly incorporated in the dilution compartments, while the process according to US-A-5120416, the balls are mobile and it is possible to introduce them in the dilution compartments and extract them from those compartments, by means of circulation in the form of suspension. known applied to water, the resins are presented in a mixed bed of strong cationic and strong anionic type. The invention relates to a process for the demineralization of sweet whey from cheese-making, characterized in that a sweet whey from a more or less concentrated cheese dairy is electrodeionised in an apparatus whose dilution compartments or the concentration and dilution compartments contain resins balls constituted by cationic resin alone or with a mixture of cationic resin and weak anionic resin and which regulates the pH of the concentration compartments, to a value lower than 5. In the frame of the invention, it is designated by sweet whey of cheese , the liquid obtained after the coagulation of casein by rennet at the time of cheese making. The raw material can be crude, more or less concentrated and also reconstituted in an aqueous medium from dust. Any material customarily used in the exchange of ions, for example macro-reticulated, in the form of a gel or macroporous, can be used as a resin, as long as that material has the rigidity compatible with confinement in cells and does not fix the proteins by absorption or adsorption. . A mixture of cationic resin and weak anionic resin can be used. As the cationic resin, a weak or strong cationic resin or also a mixture of these resins can be put into operation. A weak cationic resin generally has a high adsorption capacity and relatively large swelling. A strong cationic resin has a weaker adsorption capacity and limited swelling. According to a preferred embodiment of the process, the electrodeionization is carried out with a mixture of strong cationic resin beads alone in the dilution compartments. With this embodiment, we have noted that the demineralization of the anions that are to be eliminated, essentially CI ~ and citrates, as well as that of the cations, essentially K +, Na +, Ca ++ and Mg ++, was carried out satisfactorily without noticeable losses of proteins, with the advantage of a better microbiological quality at a temperature of about 30 ° C, due to the work that leads to a low final pH, of the order of 3 to 4. On the other hand, nitrogen decreased, which increased the percentage of true protein content, sought in particular in children's products and for the same occasion modified the aminogram of the product. According to a variant, the electrodesionization with strong cationic and weak anionic resin balls is carried out in a mixed or stratified bed in the dilution compartments, or in the dilution and concentration compartments, preferably in the proportions weights strong cationic resin / weak anionic resin of 30% -40% / 70% -60%. The strong cationic resin is preferably in the H + form and the weak anionic resin preferably in the OH form. "We have noticed that, when the concentration compartments were filled with a mixed bed or when those compartments were empty, the pH increased. in the course of demineralization, this fact, combined with an increase in the concentration of calcium and phosphorus, came from the dilution compartments, causing a regular fall in flow and an increase in pressure in that compartment. Due to the precipitation of the calcium phosphates, it is essential to reduce this phenomenon by preventing the pH from exceeding 5. In order to do this, an aqueous solution of acid, for example HCl, is added, preferably by means of a pH-stat This measure is not necessary when the concentration compartments are filled with cationic resin alone, which Pawns the role of lowering the pH by continuously releasing the H + ions. It has also been observed that the conductivity decreased in the electrode compartments in the course of the demineralization. When the conductivity becomes too low in those compartments, there is a decrease, even a stop of the demineralization. To avoid this, a continuous acid is added, for example an aqueous solution of sulfuric acid, so as to maintain the conductivity at a value compatible with a correct demineralization, for example at a value >; 5-20 ms. When a significant deanionization is desired, it is preferable to increase the pH of the substrate, either at the beginning of the demineralization process, or when the demineralization rate reached approximately 70%, at a value of 7.5-8 approximately, by alkalization, for example by a strong base such as KOH. In a variant, Ca hydroxide can be added and, if necessary, heated, for example, at 45 ° C for 20 minutes, and then removing the precipitate that formed. Another variant of this deionization consists in passing the substrate, for example demineralized to approximately 80%, through a column of weak anionic resin. The process according to the invention can be put into operation in continuous mode, in which case the substrate, on the one hand, can be directed towards the dilution compartment of the module, and then evacuated from that compartment little by little in the form of a demineralized product and , on the other hand, the washing flow can be directed towards the concentration compartment and, according to the versions, the brine or diluted hydrochloric acid can be evacuated from it, little by little. In a variant of commissioning, in batch mode or by means of charges, the substrate can be recirculated back through the dilution compartment and the brine is recirculated back through the concentration compartment, until the rate is reached. demineralization sought. After the demineralization, if this is the case, the reactant obtained can be neutralized by the addition of an alkali, preferably of food grade, and then dried, for example by spraying in a drying tower. The product obtained with the implementation of the process according to the invention that is liquid or powder, can serve as an ingredient in the manufacture of a food that is intended for human or animal food. Above all, it can be used as a substitute for lactoproteins, that is to say a de-lactated product containing, in particular, from 30% to 40% by weight of proteins and from 45% to 55% by weight of lactose or a demineralized lactosergic product which contains, in particular, from 9% to 15% by weight of proteins and from 75% to 85% by weight of lactose. It can be used in substitution of milk or whey, as an ingredient in the manufacture of confectionery products-chocolate or iced confectionery, and in particular as a substitute of whey in the manufacture of children's products, especially milk adapted to breast milk . The method according to the invention will be described in more detail, referring to the attached drawing whose figure 1 schematically represents a simplified electrodeionization apparatus. For simplicity, a single sequence of alternating cells is represented, whereas in reality a module comprises several sequences of alternating cells, arranged in parallel.
In Figure 1, module 1 comprises an alternation of semi-permeable polymer membranes 2a, 2b, cation permeable and anion impermeable, negatively charged, for example by sulphonic groups and 3a, 3b, permeable to anions and waterproof to cations, positively charged, for example containing quaternary ammonium groups between electrodes, an anode 4 and a cathode 5. Membranes 2b and 3a delimit a cell filled with resin beads, for example strong cationic 6 and weak anionic 7, in mixed beds, which constitute a dilution compartment 8 surrounded by two spacers delimited respectively by membranes 2a, 3a and 2b, 3b, filled with resin or free of resin, forming the concentration compartments 9a, 9b. The anode 10 and cathodic compartments 11 surround the concentration compartments 9 a, 9 b located at the ends of the module. The apparatus works in the following manner: The substrate flow to be demineralized 12 passes through the dilution compartment 8 in which its cations such as C + adsorbed by the strong cationic resin and its anions such as A "adsorbed are removed. By the weak anionic resin, under the effect of the electric field, created between the electrodes, the anions are directed towards the anode 4, pass through the membrane 3a and are rewired by the membrane 2a, in parallel, the cations are directed towards the cathode 5. , they pass through the membrane 2b and are returned by the membrane 3b, resulting in an impoverishment of the substrate 12 in ions, which is discharged in the form of demineralized reagent flow 13 and an ion enrichment of the flow of washing solution 15 that enters in the concentration compartments 9a, 9b, from which they are evacuated in the form of brine flow 14. These flows constitute the hydraulic circuit of the storage compartments ntration, CHC. Concomitantly, cations pass from the anodic compartment 10 to the concentration compartment 9a through the membrane 2a and are returned to the level of the membrane 3a, while the H + ions migrate through the entire module and regenerate the balls of strong cationic resin. In parallel, anions pass from the cathode compartment 11 to the concentration compartment 9b through the membrane 3b and are returned to the level of the membrane 2b, while the OH ions "migrate through the entire module and regenerate the resin beads. weak anionic.A total electrolysis of the water that provides the regeneration ions is produced.The flows that circulate in the anodic and cathodic compartments and from one to the other, constitute the hydraulic circuit of the electrode compartments, CHE. In the following, the percentages and parts are by weight, unless otherwise indicated: - prior to processing, the reconstituted raw materials of powders were centrifuged at 2000 g or filtered, in order to remove solid particles that may clog the module - the analytical values were obtained with the following methods: * true protein content: calculated from measurements with the Kjeldhal method of total nitrogen (TN) and non-protein nitrogen (NPN), such as: (TN-NPN) x 6.38; * ash determined by calcination at 550 ° C;* percentages of cation content (Ca ++, Mg ++, Na +, K +) and in phosphorus: measured by atomic absorption stereography (ASS); * percentages of citrate and lactate content: determined by enzymatic methods (Boehringer Mannheim, 1984); * percentage of content in Cl: measured by potentiometric titration with AgN? 3 with a silver electrode.
BJKMPhQS i? i The modules are rinsed thoroughly, whose dilution and concentration compartments contain specified resin balls with distilled water and the different compartments are filled in the following manner: - the electrode compartments with 4 liters of an aqueous solution of Na2S04 at 7 g / l whose pH is adjusted to 2 with H2SO4; - the concentration compartments with 4 liters of an aqueous solution of 2.5 g / l of NaCl; - the dilution compartments with 2.5 kilos or 8 kilos of the substrate that will be demineralized. After 10 minutes of recirculation to stabilize the pressure of the different compartments, 400 ml of the substrate of the dilution compartment are taken, weighed and reserved for analysis. The voltage is set to the maximum value of 28 V, the electric current begins to circulate between the electrodes and the demineralization begins. The conductivity, the temperature and the pH in the different compartments are monitored continuously and the demineralization is continued until a conductivity decrease of 90% / 95% in relation to the conductivity of the starting substrate. The demineralization takes place discontinuously, by loading, ie by recirculating the substrate through the module until the total volume of the charge has reached the target-set conductivity. In the examples comprising a treated load of8 kilos, the conductivity of the concentration compartment (which provides the flow that collected ions) is maintained at a value of > 30 ms (Siemens mill) replacing half of the solution with distilled water when this conductivity value is reached. At the end of the demineralization process, ie when the demineralization rate that is selected a priori is reached, which is not the maximum possible demineralization rate, the current is cut off, the total volume of the demineralized reagent, ie the permeate, is collected. , it is weighed and dried by lyophilization. The same procedure is followed with the brine from the concentration compartment or part retained and with the solutions from the electrode compartments. Finally, the module is rinsed several times with distilled water or, if necessary, washed with a solution containing 2.5% NaCl / l% NaOH or with a solution of 5% NaCl / 1% Na percarbonate, Rinse with distilled water and keep it filled with water between charges. The operating conditions and the results obtained are indicated in table 1 below.
TABLE 1Example 1 2 Type of resin HPlll (form) HPlll (form H +) mixture H + / HP661 (form / HP66K OH form ") strong cationic% OH") Rohm & Haas Rohm & Haas 40/60/ anionic 40/60 weak sweet whey preconcentrated by evaporationSweet whey 6.7 18.2 material, dry (%) Flow rate (1 / min) 0.7 0.7 Duration of 35 94 treatment (min) Final pH 4.1 5.35 Rate 91.76 87.13 Demineralization (%) TN lost in% from 11.51 8.96 start True protein 6.39 5.2 lost in% of the startBy way of comparison, when using the module without resin in the compartments, with a sweet whey at 6.7% dry matter and flows of 0.7 and 1.4 liters / minute respectively, considerably longer times, 110 minutes and 140 minutes respectively are needed to obtain a demineralization rate of 84.6% and 82.1% respectively. In addition, when the module is used with normal strong cationic / strong anionic resins in mixed bed with whey flow rates ranging from 0.7 to 1.4 liters / minute, with percentages of dry matter content ranging from 6.7% to 19.8% for 28 a 70 minutes, demineralization rates of 85% to 91% are obtained, but with losses in true proteins that are between 7.6% and 9.3%. EXAMPLE 3 Proceed as in Examples 1 and 2, to the demineralization of a sweet cheese whey, but which was previously concentrated by nanofiltration on DDSR module, with plate and frame equipped with APV HC50R membranes, at a pressure of about 35 bars , up to a rate of 19.8%. The operating conditions and the results obtained are shown in Table 2 below.
TABLE 2Type of resin, mixture HPlll (form H +) / HP661 (strong for-cationic /% anionic OH ~) Rohm & Haas, 40/60, weak% sweet whey, preconcentrated by nanofiltrationSweet whey, dry matter 19.8 (%) Flow rate (liter / minute) 1.4 Duration of treatment 120 Final pH 4.98 Demineralization rate (%) 91.79 TN lost in% of start 9.85 Real protein lost in% of start 5.21EXAMPLES 4 V 5 Proceed as in Examples 1 to 3, but filling the dilution compartment with only one type of resin, strong cationic HPlll, Rohm & Haas, under H + form. In addition, the different compartments are filled in the following manner: - the electrode compartments with 4 liters of an aqueous solution of H2SO4, 0.025 M; - The concentration compartments with 4 liters of an aqueous solution of HCl, 0.015 M; - the dilution compartments with 5 or 8 kilos of substrate that will be demineralized.
The treatment conditions as well as the results are indicated in table 3 below.
TABLE 3Example 4 Sweet whey, 6.7 6.7 dry matter (%) Duration of treatment28 25 minutes (minutes) Flow rate (liters / minute) 0.7 1.4 Final pH 3.06 3.69 Deminerali rate95.02 83.88% (%) TN lost in% of 8.45 2.14 Initial Real protein 1.27 - 2.27 from the beginningLegend: "-" means that a part of the non-protein nitrogen disappears from the substrate at the time of treatment, which explains a negative loss and therefore a real protein gain. By way of comparison, when using the module without resin in the dilution compartment, with a whey at 6.7% dry matter and at flow rates of 0.7 to 1.4 liters / minute respectively, considerably longer times, 110 minutes and 140 minutes are required respectively, to obtain a demineralization rate of 84.6% and 82.1% respectively. In addition, when the module is used with normal strong cationic / strong anionic resins in mixed bed with whey flow rates ranging from 0.7 to 1.4 liters / minute, with percentages of dry matter content ranging from 6.7 to 19.8 for 28 to 70 minutes , demineralization rates are obtained from 85% to 91%, but with true protein losses that are between 7.6% and 9.3%EXAMPLE 6 Proceed as in example 2 to the demineralization of a fresh whey from pre-concentrated cheese, but filling the dilution compartment with a mixture of 40% / 60% strong cationic resin, HP-111 (form H +) / anionic resin weak, HP-661 (OH form "), Rohm &Haas leaving the concentration compartment empty, After 30-40 minutes, the pH in the concentration compartment increased to a value close to 5, and a decrease is noted regulate the flow rate and increase the pressure in that compartment.The pH is then kept below 5 by automatic compensation by adding a 30% aqueous solution of HCl, for example by means of a p -stat.
A decrease in conductivity in the electrode compartments is also noted, which is maintained at 5-20 mS by continuously adding an aqueous solution of sulfuric acid.
JEM LO 7 Proceed as in example 2 to the demineralization of a sweet whey from pre-concentrated cheese, but filling the dilution compartment with a mixture of 40% / 60% strong cationic resin, HP-111 (form H +) / resin weak anionic, HP-661 (OH form "), Rohm &Haas and the concentration chamber with the strong cationic resin, HP-111 (form H +) .In these conditions, it is the strong resin that maintains the pH in the field On the other hand, conductivity is maintained in the electrode compartments at 5-20 mS by continuously adding an aqueous solution of sulfuric acid.
EXAMPLE 8 The procedure is as in Example 5, except that, once the level of 75% demineralization has been reached, the pH of the substrate entering the apparatus is adjusted to 7.5 / 8 by the addition of an aqueous solution. of KOH, and the pH is maintained at this value up to a demineralization level of 90%. In this way, a significant reduction in the amount of anions present in the final liquid whey is obtained, in comparison with what is obtained without prior adjustment of the pH.
TAfiLft 4Anions AnioAnioAnioAniode de nes nes nes nes nes nes to final game final final final game(g / kg) (eq./kg) without sin with adjustment adjustment adjustment adjustment previous previous previous of the pH of the pH of the pH of the pH (g / kg) (eq./kg) to 7.5 to 7.5 (g / kg ) (eq / kg)2. 86 0.085 0.454 0.14 0.3 0.009